What if Adam Lanza was Amanda Lanza? How would that change the national dialogue around the Newtown tragedy? Here's how: the first topic on everyone's agenda would be the gender of the perpetrator. Why would a woman do something like this?

So why aren't we asking the same question about the actual shooter? Do we simply take it for granted that rampage killings are a guy thing?

We need to honestly discuss why 61 of the last 62 mass killers in the U.S. have been men. This is not the result of random forces. It might be true that, overall, only a tiny percentage of men and boys commit mass murder. But there's a reason so many young men -- and not young women -- have carried out these despicable acts. Simply stated, our culture of hyper-masculinity encourages boys to use dominance, aggression and control as a means to an end, rather than deal with their emotions and express themselves in healthier ways.

Some form of mental illness may have played a role in Adam Lanza's murderous outburst, as well as in other rampage killings. But this raises another key question about gender. The Amandas of our society have mental illnesses too. Why don't they act them out in violent attacks on innocent children, moviegoers and worshipers from different faiths? Our girls have eating disorders and episodes of self-mutilation, but they don't turn their anger and fears and anxieties into violent acts on others. They go inwards, just as our boys have been taught to go outwards. It shouldn't be a surprise so few girls become school shooters.

After all of the changes prompted by multicultural women's movements over the past decades, we still devalue teaching empathy to our boys and define vulnerability as weakness. We define manhood less through qualities like caring and compassion and more though aggression and violence. Consequently, we send a message to emotionally and psychologically vulnerable boys and young men that we don't care about them — which can only fuel their rage and fantasies of revenge.

There is much to be done if we are going to prevent future Newtowns.

In addition to policy shifts in gun control and mental health services, we need to look inward and start making cultural changes. We need to stop equating manhood with aggression and violence. This won't be easy, as media corporations make fortunes selling narratives in movies, TV shows and video games that reinforce this stifling vision of masculinity. At the very least, all of our children should have access to gendered media literacy education that gives them the analytic tools to understand how the media influences their thinking -- and how they can safely and non-violently fight back.

Furthermore, we have to expect and demand more from our leaders, inside and outside of politics. Especially our men. We need more men in positions of political and cultural leadership who are willing to stand with women and change the national conversation.

To that end, we ask President Obama and the leadership of both parties to convene a meeting of men and women who work with boys and young men in schools, juvenile justice and other areas, and of experts on men's violence, such as batterer intervention counselors. Together these leaders will discuss how we can work together to define manhood in more affirming and less toxic ways -- to redefine strength in men not as the ability to impose your will through guns or violence, but the ability to take a stand for nonviolence. Perhaps then, future generations could be raised in a much safer society.

Jackson Katz is co-founder of Mentors in Violence Prevention and the author of Leading Men: Presidential Campaigns and the Politics of Manhood. Jennifer Siebel Newsom is the filmmaker of the documentary Miss Representation and the founder and CEO of MissRepresentation.org, a call-to-action movement for women and girls. They wrote this for this newspaper.